Metadata Report for BODC Series Reference Number 2118632

• Metadata Summary

• Problem Reports

• Data Access Policy

• Narrative Documents

• Project Information

• Data Activity or Cruise Information

• Fixed Station Information

• BODC Quality Flags

• SeaDataNet Quality Flags

Metadata Summary

Problem Reports

No Problem Report Found in the Database

Data Access Policy

Public domain data

These data have no specific confidentiality restrictions for users. However, users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgment.

The recommended acknowledgment is

"This study uses data from the data source/organisation/programme, provided by the British Oceanographic Data Centre and funded by the funding body."

Narrative Documents

Marianda Versatile INstrument for the Determination of Total inorganic carbon and titration Alkalinity (VINDTA) 3C

The VINDTA 3C (Versatile INstrument for the Determination of Total inorganic carbon and titration Alkalinity) is a laboratory alkalinity titration system combined with an extraction unit for coulometric titration, which simultaneously determines the alkalinity and dissolved inorganic carbon content of a sample. The sample transport is performed with peristaltic pumps and acid is added to the sample using a membrane pump. No pressurizing system is required and only one gas supply (nitrogen or dry and CO2-free air) is necessary. The system uses a Metrohm Titrino 719S, an ORION-Ross pH electrode and a Metrohm reference electrode. The burette, the pipette and the analysis cell have a water jacket around them. Precision is typically ± 1 µmol kg^-1 for TA and/or DIC in open ocean water.

Further details can be found in the manufacturer's brochure.

Non-toxic (underway) sea water supply

A source of uncontaminated near-surface (commonly 3 to 7 m) seawater pumped continuously to shipboard laboratories on research vessels. There is typically a temperature sensor near the intake (known as the hull temperature) to provide measurements that are as close as possible to the ambient water temperature. The flow from the supply is typically directed through continuously logged sensors such as a thermosalinograph and a fluorometer. Water samples are often collected from the non-toxic supply. The system is also referred to as the underway supply.

Discrete Underway Dissolved Inorganic Carbon and Total Alkalinity Samples for RRS Discovery Cruise DY031

Originator's Protocol for Data Acquisition and Analysis

61 underway samples were collected from the ship's non-toxic system, for the majority of the cruise once every 4 hours. Any samples (both profiles and underway) collected after 20:00 on the 14th of June were poisoned with 50l 50% mercuric chloride solution and were analyzed back at the National Oceanography Centre (NOC).

Sampling and analysis for carbonate system parameters broadly followed the standard operating procedures outlined by Dickson et al. (2007). For more information see the cruise report.

DIC:

Dissolved inorganic carbon (DIC) was determined by coulometric titration. An automated extraction line took a 20 mL subsample which is subsequently purged of CO₂ in a stripping chamber containing ~1 mL of ~8.5% phosphoric acid (H₃PO₄. A stream of nitrogen carried the CO₂ gas into a coulometric titration cell via a condenser, to strip the gas flow of any water. The CO₂ reacted with the cathode solution in the cell to form hydroxyethylcarbamic acid, which is then titrated with hydroxide ions (OH-) generated by the coulometer. The current of the coulometer was then integrated over the duration of the titration to obtain the total amount of carbon titrated.

TA:

Determinations of total alkalinity were performed by acid titration that combines aspects from both the commonly used 'closed cell' method and the 'open cell' method, following the VINDTAs standard settings. A single 10 L batch of acid of ~0.1M and salinity 35 was prepared to be used by both VINDTAs. Potential drift in acid strength due to HCl^-gas loss to acid vessel headspace was not accounted for.

References

Dickson, A.G., Sabine, C.L. and Christian, J.R. (Eds.) 2007. Guide to best practices for ocean CO2 measurements. PICES Special Publication 3, 191 pp.

BODC Data Processing Procedures

The sample data were supplied to BODC in excel. Data received were loaded into the BODC database using established BODC data banking procedure. Originator's parameters were mapped with BODC codes as follows:

Project Information

NOCS National Capability

The National Oceanography Centre Southampton National Capability focuses on long term science concerned with basin/decadal variability of the Ocean.

Data Activity or Cruise Information

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

Fixed Station Information

Extended Ellett Line

The Extended Ellett Line is a hydrographic transect consisting of 64 individual fixed stations which have been occupied, typically on an annual basis, since September 1996. The Line runs from the south of Iceland, across the Iceland Basin to the outcrop of Rockall, and across the Rockall Trough to the north west coast of Scotland (see map). CTD dips and associated water sampling for the analysis of nutrients are routinely performed during each station occupation.

The Extended Ellett Line augments the original Ellett Line time series - a shorter repeated transect which encompassed those stations between Rockall and Scotland. Work on the Ellett Line was typically carried out at least once a year between 1975 and 1996.

Map of standard stations (1996-present)

Map produced using the GEBCO Digital Atlas

The white triangles indicate the nominal positions of the Extended Ellett Line stations visited since September 1996. Measurements made along the Extended Ellett Line lie within a box bounded by co-ordinates 56° N, 21° W at the south west corner and 65° N, 6° W at the north east corner.

Nominal Extended Ellett Line stations (September 1996-present)

Listed below are nominal details of the standard hydrographic stations that form the Extended Ellett Line. The majority of these stations have been sampled since the outset, although several have been added more recently.

Occupations of the Extended Ellett Line (September 1996-present)

* These cruises only surveyed the original hydrographic section between Scotland and Rockall.

Related Fixed Station activities are detailed in Appendix 1

BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Appendix 1: Extended Ellett Line

Related series for this Fixed Station are presented in the table below. Further information can be found by following the appropriate links.

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